1. Field of the Invention
The present invention relates to providing sharp bend tolerant segments between relatively non-bendable cable sections in a multi-section sonar array cable. Multi-section sonar arrays have been known to suffer damage while being hauled aboard ship using a small radius capstan, or while being hauled manually over the rail of the ship. The non-bendable portions transfer the bending stresses to the bendable portions between the adjacent cable sections with the result that the electrical wires contained therein are flexed excessively and tend to fail prematurely as a result of repeated bending in the area of the joint between the adjacent cable sections.
2. Description of the Prior Art
Sectionalized marine seismic cable of the type having individual cable sections joined by articulated connector assemblies that permit relative bending movement between the individual cable sections are known. See U.S. Pat. No. 4,450,543 issued to Neeley in May of 1984. The Neeley patent disclosure illustrates relatively non-bendable cable sections articulated to intermediate elements or devices provided between adjacent cable sections. Each such element defines two distinct joints for each end of the adjacent cable sections. This requires a relatively large housing for these joints so that the wiring can be provided in a loose loop between the end of one cable section and the end of the adjacent cable section. The present invention seeks to obviate the need for an enlarged housing with two ball and socket style joints defined in the coupling element itself as suggested in Neeley.
Harris U.S. Pat. No. 3,459,873 is similar to the disclosure of Neeley in that relatively inflexible elements are connected by an intermediate housing defining two ball and socket joints with a loose wire provided therebetween. Here again the present invention seeks to obviate the need for a relatively rigid intermediate connecting link defining discrete pivotal joints for accommodating the bending required in the deployment and retrieval of a sonar array cable at sea.
Floessel U.S. Pat. No. 3,823,249 shows a conductor assembly comprising a number of relatively rigid straight sections arranged in end-to-end relationship, and connected to one another by short flexible sections that together accommodate bends of 180.degree. by reason of each intermediate section containing a coil of wire adapted to bend through approximately 45.degree.. Here again the intermediate bendable sections require considerable cable length to achieve the desired degree of bending. The present invention on the other hand accommodates a considerable bend angle, without sacrifice to excessively lengthening the overall cable in order to accommodate a plurality of such coupling elements or segments between adjacent non-bendable cable sections.
Klostermark U.S. Pat. No. 3,639,864 represents a typical prior art approach to providing flexibility in an otherwise relatively non-bendable cable of the type with which the present invention is adapted for use. However, in Klostermark the wiring provided between adjacent non-bendable cable sections must itself be flexed through approximately 180.degree.. Such a configuration can lead to premature failure of the wire and damage to the surrounding cable, sleeve or covering hose.
The above-described prior art approaches to protecting the junction between relatively non-bendable cable sections and a relatively short cable coupling element or segment, such as would be connected between a hydrophone array in one cable section and electronically controlled transmitters in an adjacent cable section, all suffer from the disadvantage that the hinge or joint between the cable sections must be designed to fold, and that consequently the wiring provided inside these prior art coupling elements is subjected to bending at severe angles, repeated flexing, and abrupt changes in tension loads. Such severe handling of multi-section cable equipped with these prior arts coupling subassemblies takes its toll on the wires where the wires emerge from the relatively hard or stiff cable sections. Furthermore even the use of relatively soft polyurethane material in this area to alleviate such bending stresses has not eliminated this problem. Unless actual strain relief is afforded to the flexible wire at the juncture between it and relatively hard or stiff potting material failures can occur. Consequently, after relatively short periods of time in service, mechanical fatigue and consequent electrical failure of the wiring can be expected with such prior art solutions.